Effects of First Diagnosed Diabetes Mellitus on Medical Visits and Medication Adherence in Korea

Background: The National Health Insurance Service (NHIS) conducted a screening test to detect chronic diseases such as hypertension and diabetes in Korea. This study evaluated the effects of health screening for DM on pharmacological treatment. Methods: The data from qualification and the General Health Screening in 2012, the insurance claims of medical institutions from Jan 2009 to Dec 2014, and the diabetic case management program extracted from the NHIS administrative system were used. Total 16068 subjects were included. Visiting rate to medical institution, medication possession ratio and the rate of medication adherence of study subjects were used as the indices. Results: The visiting rates to medical institutions were 39.7%. The percentage who received a prescription for a diabetes mellitus medication from a doctor was 80.9%, the medication possession ratio was 70.8%, and the rate of medication adherence was 57.8%. Conclusion: The visiting rate, medication possession ratio and rate of medication adherence for DM medication were not high. In order to increase the visiting rate, medication possession ratio and rate of medication adherence, NHIS should support environment in which medical institutions and DM patients can do the role of each part.


Introduction
Diabetes mellitus (DM) is a primary risk factor for myocardial infarction and stroke (1). The prevalence of DM among people who are more than 30 yr old in Korea increased from 8.6% in 2001 (males: 9.5%, females: 7.9%) to 11.0% in 2013 (males: 12.8%, females: 9.1%) (2). The death rate associated with DM in 2013 was 21.5 per 100000 people, ranked fifth among the 10 leading causes of death in Korea (3). Furthermore, in 2012, the medical insurance expenditures for patients with DM totaled approximately US $ 1.2 billion and accounted for 3.03% of all medical insurance costs (4). Despite the high so-cial and economic burdens related to DM, the management levels for this disorder in 2013 were only a 74.3% recognition rate, a 65.9% treatment rate, and a 16.3% control rate. Significant gaps remain between the 2013 recognition and control rates and the objectives suggested by the third Korean national health promotion program, National Health Plan 2020, which suggests an 85% recognition rate, 65% treatment rate, and 35% control rate by 2020 (5). Therefore, the early diagnosis and treatment of DM are critical in order to increase the recognition, treatment, and control rates for DM.
In Korea, the National Health Insurance Service (NHIS) annually or biennially conducted a screening test, the General Health Screening (GHS) that aimed to detect chronic diseases such as hypertension or DM (6). The participation rate for the GHS increased from 43.2% in 2002 (5380998 examinees) to 72.9% in 2012 (11419350 examinees) (6). Evaluations on the GHS have been performed from the perspective of its effectiveness with cost (7)(8)(9) or without cost (10-13). Nevertheless, the development of GHS in terms of quality and quantity is achieved; the assessment for the treatment subsequent to early diagnosis through GHS remains uncertain (14). There have been lots of studies on the medication adherence for DM and its related factors (15)(16)(17)(18)(19)(20)(21)(22), but only a few studies about effect of first DM diagnosis on the medical visit for the early pharmacological treatment and medical adherence. This study evaluated the effects of GHS for DM on early pharmacological treatment by investigating the visiting rates to medical institution, the medication possession rate (MPR), the rate of medication adherence (RMA) and their related factors among people firstly diagnosed with DM through the GHS in 2012 in Korea.

Methods
This study included the 2012 GHS' participants diagnosed with DM and required pharmacological treatment simultaneously (Fig. 1).
Diabetes Care, 27: 2149-2153 The exclusion criteria were as follows: 1) participants who visited medical institutions due to hypertension, DM, or other related diseases as their principal or secondary diagnosis within the previous 3 yr of the date of the second-step con-firmatory test, 2) participants with a history of a diagnosis and/or pharmacological treatment of hypertension, hyperlipidemia, myocardial infarction, or stroke based on the questionnaire of the first-step screening test, 3) participants who had even one instance of a fasting glucose level < 126 mg/dl at a first-step screening test and/or a second-step confirmatory test, and 4) participants who were under 30 yr of age at the time of the first-step screening test. A total 15673188 individuals were the subjects for GHS in 2012 and 11419350 of them (72.9%) completed the first-step screening test. Of them, 415741 participants were subjects for the secondstep confirmatory test of DM for having a fasting glucose level ≧126 mg/dl, and 156380 (37.6%) completed the second-step confirmatory test. Based on the results of the second-step confirmatory tests, 58362 participants were diagnosed with DM and also required pharmacological treatment. After 46 participants were excluded from the subject pool due to duplicate second-step confirmatory test results, 58316 participants remained. Of them, 39941 were excluded by the exclusion criterion. Thus, 16068 subjects were included in the analyses of this study. This study analyzed the data from qualification and GHS in 2012, data from the insurance claims of medical institutions from Jan 2009 to Dec 2014, and data from the diabetic case management program extracted from the NHIS administrative system. The qualification data were used to determine gender (male/female), age, and type of insurance policy, case management program for diabetes. The GHS data were used to determine the family history of DM, smoking status, drinking frequency, obesity level, blood pressure levels, and blood glucose levels. The insurance claim data were used to determine the time of the first visit to a medical institution, hospitalization history, the number of outpatient clinic visits, and the number of prescription days for DM medication. The definition or explanations of variables or its subgroups were described in Table 1. People who received the DM prescription

Data analysis
All statistical analyses were conducted with SAS software (version 9.1; SAS Institute Inc., Cary, NC, USA). A chi-square analysis, t-test, or analysis of variance was used for comparison within subgroups of variables on the rate of visiting a medical institution, the MPR, and the RMA. Next, a multivariable logistic regression analysis was performed to identify variables significantly related to visiting a medical institution and RMA. The odds ratios (OR) and 95% confidence intervals (CI) of visiting rate were calculated. A P-value<0.05 was considered to indicate statistical significance.

Ethics
This study was reviewed and approved by the Institutional Review Boards of Konkuk University Hospital (approval number: KUH1260021).

Medication
Possession Ratio = Sum of the prescribed days within the time period of denominator × 100 One year from the first prescribed day (365 d) Of the subjects who visited a medical institution, the percentage who received a prescription for a DM medication from a doctor was 80.9% (n=5195), their MPR was 70.8%, and the RMA was 57.8% (Table 3).

Discussion
This study aimed to determine the effects of GHS for DM on the early pharmacological treatment of Korea. The primary purpose of health screening is the early identification of individuals with diseases, and this purpose is only fully accomplished when it leads to the initiation of early treatment. This study was the first attempt to evaluate the visiting rates to medical institutions for the pharmacological treatment among those diagnosed with DM by GHS. The visiting rate to a medical institution within one year of subjects diagnosed who were with DM was 39.7%, and the visitor's median latency from diagnosis to visiting an institution was 48 d (data not shown). The National Breast and Cervical Cancer Early Detection Program in the US has an established standards requiring that women diagnosed with precancerous diseases or invasive cancers must initiate treatment within 60 d from the day of the final diagnosis. Moreover, the median times from diagnosis to treatment for invasive breast and cervical cancers are 14 and 21 d, respectively (23,24). Furthermore, more than 90% of these women who receive complete diagnostic care initiate treatment in less than 30 d from the time of their diagnosis (25). In addition, the visiting rates to a medical institution were higher in females, older age groups, subjects with a family history of DM, ex-smokers, nondrinking subjects, subjects who drank less frequently, subjects with normal blood pressure levels, and subjects with higher blood glucose levels.
The percentage of subjects who visited a medical institution and prescribed DM medication at the same time was 80.9%. 19.1% of medical institution visitors who did not receive a prescription might be encouraged to manage their diabetic status through changing health behaviors and/or medical follow-ups rather than taking prescribed DM medication. Furthermore, the MPR and the RMA were 70.8% and 57.8% respectively. A study that analyzed the insurance claims data of 40082 individuals diagnosed with type 2 DM for the first time in outpatient clinics in 2004 found that the MPR for 2 yr of hypoglycemic agents was 49.5% and that the RMA was 29.3% (19). The higher MPR and RMA observed in this study suggest that treatment environments that require a more active participation of the DM patients may result in changes that are more positive. The RMA for oral hypoglycemic medications by diabetic patients ranged from 36% to 93% for those who remained in treatment for 6 to 24 months (16). Since each study and disease has its own definitions of the evaluation methods, medication adherence, and follow-up periods for medication adherence, it is not easy to compare the results among studies. In this study, the factors related to RMA included age, family history of DM, blood pressure, and the number of outpatient clinic visits. The RMA is higher in diabetics with comorbid diseases or in those who take more than two kinds of hypoglycemic agents (20,21); patients are more likely to participate in medication treatment actively if the disease is more severe and they realize the importance of disease management. In this study, the subjects with higher blood pressure showed higher success rates in terms of MPR and RMA. This study has several limitations. First, due to the use of secondary data from health screening and medical insurance claims, it was impossible to assess the subjects' educational backgrounds or attitudes, the type or severity of DM, or the accessibility of the subjects to medical institutions. Second, because this study used a principal or secondary diagnosis code to identify the people with DM among the medical insurance claims data, diabetic patients may have been excluded from the analyses if DM was not their principal or secondary diagnosis, even if treatment was in progress. However, because subjects with a history of treatment for DM or related diseases were excluded from this study by the subject's selection process, there is a low possibility that DM was not recorded as a principal or secondary diagnosis at the time of first treatment for DM. Third, this study used MPR and the number of DM medication's prescription days to evaluate the medication adherence, but it is impossible to determine whether a patient actually purchased the medicine or ingested or not. However, the doctor's way of prescription it is meaningful from the standpoint of patients; therefore, MPR can be considered a useful measuring tool for determining the RMA (15,26). In addition, because it is almost impossible to ascertain the actual truth concerning medicine taking in retrospective research using large-scale databases, MPR is considered as the best option with which to evaluate medication adherence in general.

Conclusion
Medical institutions should notify the DM patients about their health status, encourage, and educate them to participate actively in treatment. Next, DM patients should follow physician's directions and cooperate with a physician to manage DM. NHIS should support environment in which medical institutions and DM patients can do the role of each part.

Ethical considerations
Ethical issues (Including plagiarism, informed consent, misconduct, data fabrication and/or falsification, double publication and/or submission, redundancy, etc.) have been completely observed by the authors.